Implemented reading from struct fields

tests/programs/struct.q

@@ -0,0 +1,34 @@
+struct Point {
+	x Int
+	y Int
+}
+
+main() {
+	p := new(Point)
+	assert p.x == 0
+	assert p.y == 0
+	assert p.x == p.y
+
+	p.x = 1
+	p.y = 2
+	assert p.x == 1
+	assert p.y == 2
+	assert p.x != p.y
+
+	p.x = p.y
+	assert p.x == 2
+	assert p.y == 2
+	assert p.x == p.y
+
+	p.x = p.y + 1
+	assert p.x == 3
+	assert p.y == 2
+	assert p.x != p.y
+
+	p.y = p.x
+	assert p.x == 3
+	assert p.y == 3
+	assert p.x == p.y
+
+	delete(p)
+}